As the processing power of microprocessors and digital signal processors increases, it has now become possible to produce substantially real-time three-dimensional images of a patient's tissue and moving blood flow using non-invasive ultrasound. With a three-dimensional image, a physician or sonographer is able to more accurately detect diseases or abnormalities in the patient.
The traditional method of producing a three-dimensional image, involves obtaining ultrasound data representative of echo intensity and Doppler shift from a number of planes in the body. A series of images containing both tissue and flow data is created and stored in memory. A three-dimensional reconstruction algorithm then analyzes the combined data in the series of tissue/flow images to create a set three-dimensional data, called a volume, that represents the tissue and blood flow in the patient. Because the reconstruction algorithm is applied to both combined tissue and flow data, tissue structure or flow deep within the image is often obscured when a rendering or two-dimensional representation of the volume data is produced. While this artifact can be reduced by decreasing the opacity curves used to render the data, this has the effect of decreasing the dynamic range of the image whereby faint tissue or flow cannot be seen.
Other problems associated with prior techniques of producing three-dimensional ultrasound images include compensating for the movement of the ultrasound transducer between each of the two-dimensional images used to create volume. Such movement can result in a rendered image looking jagged or blotchy. In addition, there are no mechanisms to alert a sonographer to the quality of a three-dimensional image they are creating prior to its final completion. Therefore, a user must wait until a scan is completed before seeing the results, and must repeat the entire scan if there is a problem.
Given the above problems associated with traditional methods of producing three-dimensional tissue/flow images, there is a need for an ultrasound imaging system that can produce three-dimensional tissue/flow images wherein data is not lost as a result of the rendering process and the quality of resulting images is improved.